A LATTICE DYNAMICAL MODEL FOR 4-4'-DICHLOROBIPHENYLSULFONE

摘要

A semiempirical 6-exp potential model has been used to calculate the lattice dy-namics of 4-41-dichlorobiphenylsulphone allowing for molecular flexibility. The cal-culated Raman frequencies are in agreement with the experimental ones and a soft-mode branch with a minimum at q = 0.80 6* appears which could explain the transition to the incommensurate phase with a modulation wave vector of 0.78 b*.